Happy CNY to chinese CS-ers, wishing EVERYONE prosperous days ahead, so can get the dream lens/camera!!!
A true photograph need not be explained, nor can it be contained in words.
this photo always makes me laugh
I will call you Mister Willy Wonky from now... at least until my next lesson on photography, or when I have mastered correcting wonky verticals.
for some reason, people always end up calling me willy.
anyways, i can't remember how i wrote that tutorial thing, it was a while ago. but firstly, you have to understand the few types of things that can screw up your verticals.
1) barrel distortion or pincushion distortion, this is lens characteristic, you can only correct it post process. easiest way to understand this is to look at verticals/horizontals through a fisheye lens, or examples. for normal wide angle lens, or uwa, you will usually have milder variations of barrel distortion.
2) how parallel your camera sensor is to the vertical - easiest way is to go to a wall column, where you have two verticals near to each other. alternative is to think of looking up at chopsticks memorial up close - when you look up, verticals converge - this is called the keystone effect.
for your picture, i am not sure what #1 is, since i am not a user of your lens.
#2 is present in huge quantities there - this is a problem and limitation of photography. even if you use a tilt shift lens here (mainly for the problem of keystone effect), you will probably not be able to correct that much. i couldn't say for sure though, i have had a brief encounter with a t/s lens once only.
so you have angled your camera way upwards, probably something like / relative to the vertical |.
verticals do not always need to be corrected, as i wrote.. the keystone effect can be used to great effect to emphasize the height of a building, bring out a mood of "looming", etc.
oh , and i forgot, tilt of camera, i.e. camera is not level horizontally, causing vertical tilt.
whatever the case, i do not think it is correctable here -
i used lens distort tool in photoshop cs2, even after correcting -100, the verticals were nowhere near straight:
further step correction to -97 made some parts look right, some parts not. conclusion is that there is also tilt.
verticals are easier to correct when you are trying to get them straight, i.e. ensure camera back relative parallel to the true vertical.. use centre as reference for presence of tilt. to get it 100% correct in camera, spirit level will solve all problems for sure, if used properly.
correction of verticals usually results in loss of pixels, as you can see from the print screen attached, a lot of things have started to go missing. also , there is image degradation if serious correction is done.